×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Contact US

*
*
*
*

Thanks. We have received your request and will respond promptly.

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Transversely Isotropic?

thread327-126173

Transversely Isotropic?

Transversely Isotropic?

(OP)
The question is, can I treat a Carbon/Epoxy pre-preg fabric as transversely isotropic?  If not, how do you determine the shear modulus of the fabric, G12?  MIL-HDBK-17 does not list G12 in the tables of properties for various pre-pregs, so I assume there must be an easy way to determine it, such as G12 = E21 / 4 ?

In terms of using micromechanical analysis, all the information I have been able to find is for unidirectional fabrics, and I don't feel the same theory is necessarily valid for woven fabrics.  If anyone has any insight on this, it would be much appreciated.

The weave is a 5 Harness Satin is that helps.

Thanks.

RE: Transversely Isotropic?

I don't know what version of Mil-17 you have, but G12 values (0.514E6 msi at 70F) for AS4/3502 5HS fabric are given on page 4-151 of Volume 2, Rev F.  You cannot calculate G12 from the axial modulus values.  Typical G12 values for CF/epoxy tape and fabric are in the 0.5E6 - 0.7E6 msi range.  If you have data for a similar tape material you can estimate the stiffness properties of a fabric by entering a [0/90]s laminate into a composite laminate code.

RE: Transversely Isotropic?

(OP)
I am indeed using an old version of hdbk-17.  I have decided to go the micromechanical route to get an individual ply characterization, and then approximating the weave as a 0/90 laminate.  Thanks for the reply.

RE: Transversely Isotropic?

Barbero's CADEC is quite good for micromechanics. The software is free with his book, which is worth having.

RE: Transversely Isotropic?

Regarding Chantzypoo's question, are there any software programs out there that will actually calculate the properties of an individual ply made from a woven fabric?  Something that would take into account the type of weave, fiber pitch, etc., etc. that you can then insert into the laminate analysis.  Patran laminate modeler, Fibersim, Anaglyph kind of indicate they can, but don't say what the calculations are based on, at least in their sales literature.  I have wondered if they just take the same approach as Chantzypoo decided to do and approximate the weave as a 0/90 laminate.

Tom Stanley

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login

Resources

Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Design for Additive Manufacturing (DfAM)
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a part’s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now